1. Field of the Invention
This invention relates generally to a latch bolt assembly ejection device for installation in the jamb pocket behind the strike plate of a conventional door. The invention enables a user to unlatch a door without using the door knobs or handles. In particular, this invention relates to an electro-mechanical jamb pocket latch bolt assembly release that, when activated, will expel the latch bolt assembly from the jamb pocket enabling the door to swing freely. This invention can easily be installed in an existing door frame personally by a premises owner, without the need for specialized tools or knowledge, and without the need or expense of a carpenter. and/or an electrician, typically requiring only a screwdriver and a drill for installation.
2. Description of Related Art
Conventional door latching devices frequently go unnoticed because these devices are used many times a day, everyday, and become so routine to operate that the steps required to open a latched door are often performed unconsciously. While the standard latching device is generally suited for most applications, including latching the interior and exterior doors of a home or office, the act of disengaging a latch bolt assembly from the jamb pocket in a conventional door is not routine or easy for every user. The conventional unlatching device is particularly unsuited for those individuals who may have difficulty accessing or operating the knob or handle of a conventional door latch assembly. Thus, it has been found that, there exists a need for a device which enables individuals to unlatch a standard door without utilizing knobs or handles in situations where the use of knobs or handles to unlatch a door is difficult, cumbersome, or even impossible.
The present invention is primarily adapted for use in conjunction with a standard residential or office door, which will now be briefly described to assist in an understanding of the present invention. The standard door is hingedly connected to the door frame, typically by three hinges, one each located at the top, middle, and bottom of the door, respectively. The latching device and knobs are located in proximity to the doorwidth (i.e., the edge of the door) opposite the doorwidth hingedly connected to the door frame.
The standard door may swing between an open and a closed position. In the open position, the door is capable of swinging freely on the door's hinges that pivotally connect the door to the door frame. In the closed position, the door can be releasably latched to the door frame by means of a door latching device. In some embodiments, the door latching device can be locked, depending on the sophistication of the latching device. If the door latching device can lock, the device must be unlocked before the door can be unlatched from the door frame. In most instances, latching and unlatching the door from the door frame is accomplished by the use of door knobs or handles.
The conventional door latching device generally comprises the following components: a latch bolt assembly; door knobs; a mechanism to control the position of the latch bolt assembly as directed by the door knobs; and a jamb pocket. The latch bolt assembly is typically a spring-biased element or elements which protrude through a mortise in the front plate. The front plate is a generally flat, metallic component that is fastened to the doorwidth adjacent the door knob(s). The latch bolt assembly may comprise both a latch bolt and a trigger bolt, or, depending on the level of sophistication, the latch bolt assembly may comprise of a latch bolt alone, without a trigger bolt. Both the latch and trigger bolts slideably move through a mortise in the front plate. For simplicity, attention will be directed to door latching devices that comprise a latch bolt alone. The present invention, however, is operable with any type of latch bolt assembly regardless of sophistication, as long as the latch bolt assembly can be slideably collapsed and ejected from the jamb pocket upon the application of a lateral pushing force.
The latch bolt assembly can slideably move between a retracted position flush with the front plate, to an extended position protruding past the front plate. Typically, the latch bolt assembly is spring-biased toward the extended position. When the door is in the closed position, the latch bolt assembly extends past the front plate and into a corresponding cavity in the door jamb, herein designated as the jamb pocket, latching the door. A strike plate is typically provided on the door jamb, and is provided with a mortise or opening therethrough which defines the entranceway to the jamb pocket. The strike plate typically is a generally flat, metallic component, that incorporates a rounded edge which follows the contour of the door jamb.
The conventional door latching device typically further includes both an inner and an outer door knob or handle, which are fixed on the inner and outer surfaces of the door, respectively, in proximity to the latch bolt assembly. Some door latching devices enable only one door knob to direct the latch bolt assembly, leaving the other free to rotate without affecting the latch bolt position. Other door latching devices employ locking devices in the form of push buttons or keys which disable that door knob to direct the latch bolt assembly until the locking device is disarmed.
The mechanisms to control the position of the latch bolt assembly as directed by the door knobs can vary among the numerous door latching devices, as one with ordinary skill in the art will understand. For example, cylindrical key-in-knob locks have a keyed outside knob. The outside knob is connected to a cylinder protruding from a chassis which in turn leads to the latch bolt assembly. Rotation of the outside knob controls displacement of the latch bolt assembly. In tubular privacy locks, which are used on interior doors to prevent entry, the inside knob, which is provided with a push button or thumb turn for locking and unlocking the assembly, extends outwardly from a spindle which in turn connects to the latch bolt assembly.
Lastly, the jamb pocket is the cavity located in the door jamb, behind the strike plate, which receives the extended latch bolt assembly when the door is in the closed position. Typically, when the door is in an open position, the latch bolt assembly extends out from beyond the front plate of the hingedly-mounted door. As the door enters the closed position, the latch bolt assembly slideably retracts as it passes across the curved portion of the strike plate. The retracted latch bolt assembly further slides along the strike plate until it reaches the opening in the strike plate, whereupon the latch bolt assembly extends under spring bias until it fully protrudes into the jamb pocket latching the door in the closed position. With the latch bolt assembly in its extended position and protruding inside the jamb pocket, the door is latched closed. Rotating either inner or outer door knob about its radial axis will retract the latch bolt assembly, freeing the door to open.
Some individuals may have some physical limitation which renders it difficult or impossible use standard door knobs. An individual in a wheelchair, for example, may have great difficulty maneuvering into a position to use a door having a standard door knob. In other situations, an individual may simply not want to activate door knobs or handles to unlatch a closed door. It may be desirable for an interior door to remain latched and in the closed position when not in use, but disengaged when an individual or an object nears the door, so that one must only apply a slight pushing force on the door itself to open it.
Several variations upon the conventional door latching device are known to exist. For example, U.S. Pat. No. 3,521,921 to Miyazaki (1970) discloses an electromagnetically actuated locking mechanism providing automatic or manually controlled locking of a door. The locked/unlocked and open/closed status of the door and lock are electrically monitored by signal lights. In one embodiment of the Miyazaki invention, a solenoid is located behind the strike plate. When a switch is closed, the solenoid is activated and pushes a head through the keeper area until the head is flush with the strike plate, thus expelling any latch or lock bolt from the keeper. This device requires the use of a solenoid and, for the typical individual, requires the assistance of an electrician and/or carpenter to wire and install the device, which may require the homeowner to incur a large expense. Further, a solenoid requires a higher current than can be supplied with conventional batteries and typically operates on AC power. Since the Miyazaki device is unsuited to be supplied with battery power, it needs to be wired to an existing power source which can also require the homeowner to incur a large expense.
Another door latch release device is disclosed in U.S. Pat. No. 4,679,834 to Gotanda (1987). The Gotanda device includes a stopper plate for engaging and releasing the trigger bolt, to release the locking of the latch bolt with the trigger bolt. The stopper plate is moved by a solenoid actuated by remote control. After the device has cycled through its trigger bolt and latch bolt displacements, the door swings freely on its hinges. Like the Miyazaki device, the Gotanda device uses solenoid technology. Also like Miyazaki installation of this device is complex and typically requires the assistance of a carpenter and/or electrician.
Finally, U.S. Pat. No. 5,474,342 to Smith et al. (1995) discloses a device for ejecting a spring latch bolt from the keeper in a door jamb. The ejection mechanism is directly connected to an electric motor which is controlled by a controller and trigger element. In another described embodiment, the Smith et al. ejection mechanism is driven by a pair of solenoids. This device is also difficult and expensive to install.
Thus it can be seen that there is a need for an electro-mechanical jamb pocket latch bolt assembly release that, when activated, will expel the latch bolt assembly from the jamb pocket enabling the door to swing freely, wherein such a device can quickly and easily be installed personally by a premises owner, without the need or expense of a carpenter or electrician, and without specialized tools. It is to the provision of such an apparatus that the present invention is primarily directed.